In the United States, young men who have sex with men (YMSM) are the only group experiencing an increase in HIV incidence. Adolescents and young adults who are diagnosed with HIV are often confronted with a wide range of difficulties as they try to integrate traditional adolescent developmental issues with the burden of living with a highly stigmatized illness. These difficulties, including psychological distress, lack of knowledge, lack of social support, and stigma, create barriers for adequately engaging in medical care. Engagement in care is crucial for youth diagnosed with HIV in order to improve both medical outcomes (e.g. access to antiretroviral medication, viral suppression, survival) and public health outcomes (e.g. viral transmission via sex). Despite the critical need for those diagnosed with HIV to engage in care, HIV+ youth demonstrate lower rates of virologic suppression and higher rates of loss to follow-up compared to adults. High implementation costs and concerns around privacy and stigma may limit the scalability of face-to-face behavioral interventions. Further, interventions for newly diagnosed HIV+ youth are typically delivered within care settings thus missing those youth who delay entering care, a critical point of loss-to-follow up in the HIV care cascade. Thus, the development and testing of innovative, mobile health applications is critical for increasing intervention uptake and optimizing engagement in care for HIV+ YMSM. High rates of mobile phone ownership and technology use among youth provide a unique platform to deliver a tailored, engaging HIV health promotion intervention. The proposed study will develop AllyQuest, an interactive mobile phone intervention for HIV+ YMSM that utilizes social networking, game-based mechanics and a story-based framework to guide behavior change. Grounded in Social Cognitive Theory, narrative communication and the principles of persuasive technology, the intervention is designed to capitalize on social involvement and target the identified barriers to care among newly diagnosed youth, namely, low HIV health literacy, lack of support, and internalized stigma. The use of character-driven narrative elements serves to increase both the entertainment appeal and overall relevance of the intervention. Using an iterative research design we will work with members of the target population and Ayogo, a global leader in the application of game psychology and health behavior change, to develop and tailor the intervention content for maximal relevance and usability for newly diagnosed HIV+ YMSM (aged 16- 24). AllyQuest will be built on the EmpowerTM platform, Ayogo's proprietary gamification platform which uses social networking and game psychology to motivate behavior change. The overall goals of this R21 application are to develop and evaluate for feasibility and acceptability a potentially high-impact interventio that improves retention along multiple stages in the continuum of care for newly diagnosed HIV+ YMSM. The successful completion of this project will provide data needed to conduct a future larger efficacy trial.